In automating the application of sealant material it became necessary to accurately control the flow of material to accommodate variations in the velocity of movement of the applicator over the surface being sealed. Heretofore, no known devices were available to provide the desired function. Most systems that incorporated flow control were designed for constant flow rate.
Additionally, air under pressure can be directed at the stream of sealant being applied to a surface to control the shape of the bead profile. This is a very desirable control that a system may possess. Previous systems have controlled the bead profile without assistance of air pressure, by controlling the flow rate to be substantially constant and applying the sealant at a constant velocity. This method has the disadvantage of not enabling a controllcd variation of the bead profile